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Getting ActiveRecord to auto reconnect after lost connection (See related posts)

I puts this code in a file called active_record_hacks.rb in config/initializers but it could easily be a plugin.

   1  
   2  ActiveRecord::ConnectionAdapters::MysqlAdapter.module_eval do
   3    def execute_with_retry_once(sql, name = nil)
   4      retried = false
   5      begin
   6        execute_without_retry_once(sql, name)
   7      rescue ActiveRecord::StatementInvalid => exception
   8        ActiveRecord::Base.logger.info "#{exception}, retried? #{retried}"
   9  
  10        # Our database connection has gone away, reconnect and retry this method
  11        reconnect!
  12        unless retried
  13          retried = true
  14          retry
  15        end
  16      end
  17    end
  18  
  19    alias_method_chain :execute, :retry_once
  20  end
to rails mysql activerecord by bmarini on Mon May 19 11:47:42 -0400 2008

Comments on this post

selector37 posts on May 23, 2008 at 20:13
This isn't transaction safe. Consider the following:

   1  
   2  execute("START TRANSACTION")
   3  execute("UPDATE some_table SET do_not_delete = 1")
   4  execute("DELETE FROM some_table WHERE do_not_delete = 0")
   5  execute("COMMIT")


If you were to lose connection after the update, your marking of the records would be rolled back. Executing the delete would re-establish the connect and then run the delete outside of any transaction.

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